All of them have good planes if you play the country for a bit.
The Americans have the P40 which is good as long as you don't get in turn battle, the British have a few good ones such as the Beaufighter, HUrricane and Spitfires. Germany the MC 202 and BF 110 are dope and The LAGG is the best ive gotten from russia. Japan claims the zero. You can have fun and do great with any country honestly.